Can someone explain what to do for the following question.

What percentage of a normal distribution is greater than the mean? Give your answer correct to the nearest percent.
What formula is used? Because I have to find also 1 standard deviation of the mean and what percentage is greater than a value that is 1 standard deviation below the mean? My book does not explain this very good...

Your Z table makes it clear that the mean is right in the middle. That is 50% is greater, 50% is less.

Take a visit to
http://davidmlane.com/hyperstat/z_table.html
and you can play around with these ideas.

To calculate the percentage of a normal distribution that is greater than the mean, we can use the properties of the standard normal distribution. The standard normal distribution has a mean of 0 and a standard deviation of 1.

To find the percentage of values greater than the mean, we need to calculate the area under the curve to the right of the mean. This can be done using a Z-table or a statistical software.

Here are the steps to find the percentage:

1. Look up the Z-score corresponding to the mean in the Z-table or use a calculator. The Z-score for the mean is always 0.

2. Determine the area to the right of the mean. Since the mean is at the center of the distribution, the area to the right represents the percentage of values greater than the mean.

3. Round the value to the nearest percent.

For example, if the area to the right of the mean is 0.4005, we would round it to 40%. This means that approximately 40% of the values in a normal distribution are greater than the mean.

To find the percentage of values greater than a value that is 1 standard deviation below the mean, you can follow similar steps:

1. Calculate the Z-score for the value that is 1 standard deviation below the mean.

2. Determine the area to the right of this Z-score using a Z-table or a calculator.

3. Round the value to the nearest percent.

If your book does not provide clear explanations, you might consider searching for online resources or tutorials on the topic of standard normal distribution and how to use Z-scores to find percentages. Additionally, you can consult your teacher or seek help from a tutor to clarify any confusion you have.